Stormy Future: El Niño Could Bring Bigger Storm Surges

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Heads up, East Coast. El Niño-related weather could get even
worse in the future, according to a new study.

The coastal communities, already threatened by rising sea levels
due to climate change, may also see more
destructive storm surges from these higher waters in future
El Niño years, a new study by the National Oceanic and
Atmospheric Administration (NOAA) says. A destructive storm surge
is where storms cause water levels to rapidly increase by at
least 1 foot (0.3 meters).

The study was prompted by an unusual number of destructive storm
surges along the East Coast during the 2009-2010 El
Niño-dominated winter.

"High-water events are already a concern for coastal
communities," said study author Bill Sweet of NOAA. "Studies like
this may better prepare local officials who plan for or respond
to conditions that may impact their communities. For instance,
city planners may consider reinforcing the primary dunes to
mitigate for erosion at their beaches and protecting vulnerable
structures like city docks by October during a strong El
Niñoyear."

El Niño
conditions are characterized by unusually warm temperatures
in the equatorial Pacific that normally peak during the Northern
Hemisphere "cool season" of October to April. They occur every
three to five years with stronger events generally occurring
every 10-15 years. El Niño conditions have important consequences
for global weather patterns, and in the U.S. often cause
wetter-than-average conditions and cooler-than-normal
temperatures across much of the South.

The new study examined water levels and storm surges during the
cool season for the past five decades at four sites
representative of much of the East Coast: Boston; Atlantic City,
N.J.; Norfolk, Va., and Charleston, S.C.

From 1961 to 2010, the study found that in strong El Niño years,
these coastal areas experienced nearly three times the number of
storm surges seen in an average year. The researchers also found
that waters in those areas saw a third-of-a-foot elevation in
mean sea level above predicted conditions.

The study builds on previous ocean-atmospheric research, which
has concluded that during El Niño,
Nor'easter windstorms are more frequent along the East Coast
during the cool season.

El Niño and its impacts usually fade in the warmer months, and
may transition into La Niña conditions, which are generally
opposite to those of El Niño. However, a similar connection
between La Niña conditions and depressed East Coast sea levels
was not found.